This invention relates to a dolly for supporting a pair of wheels of a vehicle as it is being towed by a rescue vehicle such as a tow truck, and more particularly to a dolly of this type which can be safely raised and lowered by a removable jack and locked in the raised position when towing a vehicle.
It is known in the prior art to provide a dolly having four wheels between which a pair of wheels of a disabled vehicle may be cradled when towed. Such devices are necessary when the disabled vehicle cannot be towed with its own wheels on the ground. However, the prior art dollies have been deficient in some aspects, not the least of which is safety.
In some of the known apparatus the wheel carriage or cradle is fixed so that the towing vehicle must lift the disabled vehicle onto the dolly cradle, thereby providing an inconvenience in use. In other prior art dollies mechanical devices are utilized to lift and lower the cradle, the disabled vehicle being moved onto the cradle and the cradle thereafter being lifted for towing, and lowered when the disabled vehicle is removed. Some of these mechanical devices use a ratchet type mechanism which permits a step-by-step raising of the carriage, but when the carriage is to be lowered the disabled vehicle must first be lifted before being lowered. The operator must apply the lifting force and the cradle thereafter drops the disabled vehicle to the ground. Other mechanical devices use a leverage bar with which the operator applies a pivoting action lifting force and effectively manually supports the disabled vehicle as he swings the bar through the appropriate angle, but upon lowering the cradle with the disabled vehicle the force changes direction and if the operator is not braced properly there is a sudden release and the bar may be pulled rapidly from the operator's hands. These mechanical devices may therefore result in injury to the operator and/or damage to the disabled vehicle. Moreover, with the known mechanically lifted dollies, when used under conditions of ice and snow, the mechanisms can freeze and fail to operate.